This invention relates to a relates generally to the field of orthopedic medicine and more specifically to the design of an improved medical bandage formed of a moisture-curable synthetic resin material and containers for storing and dispensing such a roll form bandaging product.
Medical bandages for use in the treatment of injuries, such as broken bones requiring immobilization of a body member, are generally formed from a strip of fabric or scrim material impregnated with a substance which hardens into a rigid structure after the strip has been wrapped around the body member. The hardening substance traditionally used in carrying out this procedure is plaster-of-paris.
Conventional practice has been to fabricate a cast or splint upon an injured limb by initially applying to the limb a protective covering of a cotton fabric or the like and then overwrapping the covering and limb with a woven cloth impregnated with plaster-of-paris which has been wetted by dipping in water immediately prior to application. This practice is still in widespread use but possesses several significant disadvantages. For example, the above-described application procedure is messy and time-consuming. Several components are required and considerable skill is necessary.
In order to alleviate the above-recited disadvantages of the conventional application procedure for plaster-of-paris casts and splints, unitary splinting materials have been devised and are disclosed in, for example, U.S. Pat. Nos. 3,900,024, 3,923,049, and 4,235,228. All of these patents describe a padding material with a plurality of layers of plaster-of-paris impregnated cloth. Such unitary splinting materials are not as messy and can be applied more quickly but still suffer from a number of disadvantages inherent in plaster-of-paris cast materials. All plaster-of-paris splints have a relatively low strength to weight ratio which results in a finished splint which is very heavy and bulky. Plaster-of-paris splints are slow to harden, requiring 24 to 72 hours to reach maximum strength. Since plaster-of-paris breaks down in water, bathing and showering are difficult. Even if wetting due to these causes can be avoided, perspiration over an extended period of time can break down the plaster-of-paris and create a significant problem with odor and itching.
A significant advance in the art of casting and splinting is disclosed in U.S. Pat. Nos. 4,411,262 and 4,502,479. The casting materials disclosed in these patents comprise a flexible fabric impregnated with a moisture-curing resin enclosed in a moisture-free, moisture-impervious package. Compared to plaster-of-paris, these products are extremely lightweight, have a very high strength to weight ratio and can be made relatively porous, permitting a flow of air through the casting material. Prior art moisture-curing systems include a package within which is contained a plurality of layers of fabric, such as fiberglass, impregnated with a moisture-curing resin. No provision is made for re-closing the package, so that the entire material must be very quickly used after removal from the package since such moisture-curing resins will cure in a relatively short period of time due merely to contact with atmospheric moisture.
This technology has permitted the development of lightweight, easy to apply splints, as exemplified in U.S. Pat. Nos. 4,770,299, 4,869,046, 4,899,738, 5,003,970 and 5,415,622. Such splints now dominate the market for medical splints.
From the above discussion, it can be seen that both the conventional plaster-of-paris casting method and the more recent moisture-curable resin casting method possess both advantages and disadvantages. On the one hand, plaster-of-paris casts are bulky, heavy and difficult to apply whereas moisture-curable resin casts are lightweight, durable and relatively easy to apply. Plaster-of-paris can be very easily stored and used as needed since it has a relatively long shelf life so long as it is not completely wetted. On the other hand, the moisture-curable resins are very sensitive to the presence of even minute amounts of moisture which requires that either the materials be packaged in a wide variety of different shapes and sizes or unused portions be discarded, generating a substantial amount of waste and increasing the effective cost of the product. This invention combines the advantages of both plaster-of-paris and moisture-curable resin systems while avoiding their respective disadvantages. This is accomplished by providing a unitary splinting system with improved strength and convenience. A unitary system is provided with the use of moisture-curing resin casting materials, together with a moisture-impervious package with means for resealing the package against entry of moisture after a desired length of bandaging product has been removed for use. In this manner, hardening of the bandaging product remaining in the moisture-impervious package is prevented thereby increasing the cost effectiveness of the system substantially.
However, there are still some disadvantages to the synthetic splinting system described above. In particular, woven fiberglass fabric is typically used as the substrate which carries the moisture-curable resin. The substrate is formed of several layers of fabric, for example, warp knitted fabric, which have been cut into strips of the correct length and width. The process of cutting the fiberglass fabric to the correct size leaves cut fibers and yarns projecting outwardly from the sides and the ends of the splinting material. As manufactured, this fabric is relatively soft and flexible. Moreover, the substrate is fully enclosed with the surrounding padding material. After curing, however, the cut fibers and yarns become hard and needle-like. These projections can project through the thickness of the padding material into contact with the skin of the patient causing skin-sticks, cuts, irritation and itching. Similar problems can exist with substrates fabricated from woven or knitted thermoplastic yarns which must be cut to the proper length and width.
Moreover, the splint manufacturing process utilizing flat fabric is relatively labor intensive, since the woven or knitted fabric must be cut to the proper length and width and overlaid with other layers of fabric, usually 4 to 8, to produce the substrate. In order to properly form the substrate, the overlaid layers must be carefully aligned so that the width and thickness are even. In instances where the multiple overlaid layers are stitched together, even more labor is required.
More recently, non-woven fabrics have been introduced into the splinting field. Non-woven fabrics do provide a smoother edge that do woven or knitted fabrics. However, non-woven fabrics are thicker, inhibiting the ability of the product to conform to the extremities as easily as does the woven or knitted fabric substrates. The greater thickness also makes the it difficult to evenly impregnate or coat the substrate with resin.